Bug Fixes:
- removed ability to build wonders in areas that block rivers
- removed infinite money glitch by cancelling wonders with labor
- fixed a bug that returned the resources used when a raw goods producers ran out of raw materials

Gameplay Fixes:
- added ability to send labor to wonders by sea and by air
- added esc hotkey to close trade center menus
- set frame rate limit to 60 to reduce unnecessary GPU usage

Balance Fixes:
- set running out of money to trigger population loss to only be relevant on the hardest economic difficulty
- reduced lumber cost of Stonehenge